Electric circuit breaker



March 23, 1954 R. N. ROWE EIAL 2,673,267

ELECTRIC CIRCUIT BREAKER Filed Jan. 16, 1953 2 Sheets-Sheet l Inventors: Ra gmond N.Rowe, Eric A. Er-iqson,

Th eir- Attof'ney.

March 23, 1954 R. N. ROWE ET AL 2,673,267

ELECTRIC CIRCUIT BREAKER Filed Jan. 16, 1953 2 Sheets-Sheet 2 6a 2/ a I 26 Their Attorne g.

20 b Inventors:

' Ragmond N. -Rowe, 22 Eric A. Ericson,

Patented Mar. 23, 1954 UNITED STATES PATENT OFFICE ELECTRIC CIRCUIT BREAKER Application January 16, 1953, Serial No. 331,558

12 Claims. (01. 200-116) Our invention relates to electric circuit breakers, and more particularly to manually operable current responsively tripped electric circuit breakers of the automatic reset type.

In small air circuit breakers it is a constant eifort to provide the necessary manual opening and closing operation and automatic tripping and reset functions with a minimum number of parts, both for ease and reliability of operation and economy of manufacture.

It is therefore a general object of our invention to provide an electric air circuit breaker of the manually operable, automatically current responsively tripped automatic reset type which is inexpensive and readily assembled, While dependable and effective in operation.

It is still another object of our invention to provide a manually operable electric circuit breaker wherein the casing is automatically sealed in the on position of the breaker.

It is a more specific object of our invention to provide an operating mechanism for amanually operable current responsively tripped electric circuit breaker, in which a single actuating spring is utilized to hold the mechanism in both its open and closed circuit position, and also to automatically trip and automatically reset the mechanism after tripping.

It is still another object of the invention to utilize the same single spring of combined function to also seal the breaker casing when the breaker is closed.

In carrying out our invention in one form we provide a toggle link type of operating mechanism in which one end of an overcenter toggle linkage is pivoted upon a movable carrier memher which is normally latched and retained in fixed position by an ov'ercurrent responsive device. The opposite end of the toggle linkage bears against a compression spring; the other end of which is fixedly seated in the casing, the spring being disposed to bias the linkage for longitudinal movement toward that end pivoted on the carrier member when the linkage is in its extended position. A movable switch member is pivotally connected to the'toggle linkage adjacentto but spaced from the spring seated end of the linkage, and a fixed stop is provided for limiting movement oi th switch member in the circuit opening direction when the toggle is collapsed. A rectilinear actuating rod is connected to the knee pivot of the linkage to move the knee pivot overcenter for manual opening and closing movement. This same actuating rod limits overcenter movement of the toggle in circuit closing operation by seating against the casing, and in so doing seals the casing against entrance of explosiv gases and-the like. To permit automatic tripping operation the knee pivot i connected to the actuating rod by means of a swinging link, and this link so controls the position of the knee pivot upon tripping that the extending spring engaging end of the toggle rotates the toggle link connected to the movable switch member after engagement of the switch member with its stop, thereby to automatically collapse the toggle and restore the carrier member to a reset position.

Our invention itself will be more fully understood and its various objects and advantages further appreciated by referring now to the following detailed specification taken in conjunction with the accompanying drawing, in which Fig. 1 is a side elevational view, with the cover removed, of a manually operable current responsively tripped electric circuit breaker embodying our invention and shown in the open or off position; Fig. 2 is a similar view of the same circuit breaker shown in the closed or on position; Fig. 3 is a similar view of the same circuit breaker shown in the trip free position; Fig. 4 is a perspective view of the bimetallic latching detent included in the circuit breaker of Figs. 1, 2 and 3; Figs. 5 and 6 are side elevational and plan views, respectively, of the bimetallic member of Fig. 4 showing the member in its no load condition; Figs. '7 and 8 are similar side elevational and plan views, respectively, of the bimetallic member of Fig. 4 shown in its short circuit condition; and Fig. 9 is an exploded per spective view of the manual actuating button for the breaker shown at Figs. 1, 2 and 3.

Referring now to the drawings, and particularly to Figs. 1, 2 and 3, we have shown our invention embodied in an air circuit breaker comprising an open-sided housing I formed of suitable molded plastic insulating material and having recesses therein for the reception and retention of an operating mechanism. The housing is provided with a metal top plate 2 having return bent end. portions 3 which seat in slots (not shown) in the housing. Within the return bent end portions 3 are disposed threaded nuts 4 adapted to receive bolts (not shown) for mounting the circuit breaker upon a panel or the like. The operating mechanism is adapted to be held in place in thehousing l by a side cover plate (not shown), which is adapted to be connected to the housing by means of rivets passing through holes 5 in the housing I. The mounting nuts 4 are disclosed and claimed in a copending application of Eric A. Ericson, Serial No. 342,633, filed March 16, 1953, and assigned to the same assignee as the instant application.

Within the molded casing I is disposed a manual and automatic operating mechanism for a pail of cooperating switch contacts 6 and I. The contact 6 is stationary and is mounted upon a terminal member 8 projecting from the bottom of the casing I. The movable contact member I is mounted upon a movable switch member, shown as an L-shaped contact arm 9 pivotally mounted at a point intermediate its ends upon a fixed pivot pin III carried by the casing I. The contact arm 9 is movable between an open circuit position, shown at Fig. l, where it engages a fixed stop I I formed on the casing, and aclosed circuit position, shown at Fig. 2, where the contacts 6 and I are in engagement. A second terminal member I2 is seated in suitable positioning recesses in the housing I and projects from the bottom of the housing opposite the terminal member 8.

The L-shaped movable contact arm 9 is manually and automatically movable between open and closed circuit position by means of an automatically releasable toggle mechanism shown in the drawings in open, closed and tripped positions. The actuating mechanism, shown at Fig. 1 in its manual open position, comprises a. releasable carrier member I3 pivotally mounted upon a fixed pivot I4 fixed in the casing I, and a pair of toggle links I5 and I6 pivotally connected, respectively, to the upper ends of the carrier member I3 and the contact arm 9 by means of movable pivot pins I5a and Ifia, respectively. The adjacent ends of the toggle links are pivoted together at their knee by means of a movable pivot pin II. Th toggle link I6 is connected intermediate its ends to the pivot pin IBa, and thus includes a portion I6b extendling beyond the pin I6a and engaging a compression spring I8, the other end of which is fixedly seated in a suitable recess in the casing I.

The releasable carrier member I3 has mounted thereon at its lower end a slidable latch member I3a, biased to latching position by a spring I3b disposed between the latch member Ba and a portion of the carrier member I3. The latch member I3a normally engages a thermo-responsive latching detent shown as a thermo-deformable bimetallic member I9 mounted in a recess in the lower part of easing I. As shown at Fig. 1, the latch I3a is withdrawn from the bimetallic member I9 in the manual open position of the breaker by reason of a resetting bias exerted upon the toggle mechanism by the spring I8, as will be more fully explained hereinafter. At Fig. 2, however, it will be observed that when the mechanism is in its manual on or closed position, the latch I3a is in engagement with the bimetallic member I9, thereby normally to retain the carrier member I3 in fixed position. As will be more fully explained hereinafter, the bimetallic latching detent I9 is connected in series circuit relation between the circuit breaker terminals 8 and I2 and carries the current passing through the breaker contacts 6 and I. When. sumclently heated by this current, the detent I9 deforms downwardly thereby to disengage the latch Ito and release the carrier member I3 for movement to its tripped position, shown at Fig. 3.

For manual opening and closing operation, the circuit breaker is provided with a reciprocable actuating rod 20 supported for rectilinear movement in a collar 2! carried by the top plate 2 and having a stop shoulder 20c which acts also as a dust seal when engaging the collar 2|. At its lower end th rod 20 carries a swingable connecting link 22 which is connected to the knee pivot pin I! of the toggle mechanism.

As shown in greater detail at Fig. 9, the actuating rod 20 is formed as an insulating button 20a having connected thereto a metallic rod 201)- to which the link .22 is swingably attached. The rod 201) is encased for a part of its length in an insulating sleeve 20c and extends into the button 20a to which it is attached by. peening over a metal washer 20d. The sleeve 200 is of smaller diameter than the button 20a and when assembled the lower end of the button 20a forms a stop shoulder 20a. The button 20a is provided with an insulating cap 2 III. The entire actuating assembly comprising the rod 2%, button 20a and sleeve 20c is slidable within the sleeve 2| being limited in its upward movement by an integral annular collar 20g on the sleeve 2 0c and in its downward movement by the seating of the shoulder 290 in an annular recess 2Ia of the sleeve 2|. The sleeve 21 is fixed to the casing. As will be more evident hereinafter the seating of the button 20a in the recessed sleeve 2| serves to limit overcenter movement of the toggle mechanism in one direction and hold the mechanism. in its on" position. Thus, the overcenter spring force of the toggle itself serves to hold the actuating rod in sealing position.

The operation of the foregoing circuit breaker mechanism may now be observed in detail before proceeding with a further description of our new and improved bimetallic latching detent. In the manual open position of the breaker, as shown at Fig. 1, the toggle formed by the links I5 and I6 is broken by movement of the actuating rod 20 to its upper or withdrawn position. The toggle being broken, the compression spring It holds the contact arm 9 against the stop II, and, because of the toggle link extension I6b, biases the link I6 clockwise about the pivot pin Isa, as shown in the drawing. With the contact arm 9 engaging the fixed stop, the pivot pin Ito is held in position so that clockwise rotation of the link I6 about the pin lie (within the limit of movement permitted by the swinging link 22) draws the toggle link I5 slightly to the right as shown in the drawing, and rotates the carrier member I3 to a slightly withdrawn or reset position, as shown at Fig. 1.

When the actuating rod 20 is depressed, as shown at Fig. 2, until its stop shoulder 20c engages the collar 2 I. the knee pivot pin I1 is moved downwardly, thereby to extend the toggle links I5 and I6 and move the knee pivot II across the line of action of the spring I8 to a slightly overset position, as shown at Fig. 2. Further movement of the knee pivot 13111 H is prevented by engagement of the actuating rod shoulder 20c with the collar 2 I. In this position the shoulder 20c acts as a dust seal for the casing I the shoulder being held in sealed position by the toggle spring force. In this straightening movement the toggle links I5 and I6 force the pivot pins I5a and I6a. apart. Movement of the pivot pin I 511 is limited by engagement of the latch member Ila with the bimetallic latching detent I9, so that the pivot pin lid in the normal unreleased position of the carrier member I3 acts substantially as a fixed pivot. Thus the straightening of the toggle links I5 and I6 serves principally to move the pivot pin Ilia to the right, there by to rotate the contact arm 9 clockwise about its fixed pivot pin III and bring the contact 6 and '1 into engagement. In this position of the mechanism the knee pivot pin I! is slightly below the line of action of the spring I8, so that the pressure of the spring l8 retains the toggle in its overset position. In this position the spring I8 also tends to move the entire toggle mechanism to the left, as shown in the drawing, and longitudinally of the extended toggle links. Rectilinear movement of the entire toggle mechanism to the left is restrained, however, by latching of the carrier member I3, and thus retention of the pivot pin |5a in a normal fixed position.

'It will now be understod that reverse manual movement of the actuating rod 20, by withdrawing it from the position of Fig. 2 to the position of Fig. 1, moves the knee pivot pin I! about the line of action of the spring I8, so that the spring collapses the toggle links I5 and I6 and restores the mechanism to the open position of Fig. 1.

If, with the circuit breaker in the on position shown at Fig. 2, an overload current passes through the breaker sufiicient to deform the bimetallic strip I9 downwardly and release the latch I3a, the pressure of the spring it upon the extended toggle links I5 and It moves the links longitudinally to the left as viewed in the drawing, and rotates the carrier member I3 counterclockwise to the tripped position shown at Fig.

3. Such rectilinear movement of the entire tgthe actuating rod is manually held in its on position.

It may now be observed, however, that in moving to the tripped position shown at Fig. 3, the knee pivot pin II, being carried by the swinging link 22, has swung upward and to the left. By

this action the knee pivot is raised above the line of action of the spring l8. At the same time the link extension lBb, being rotated slightly clockwise by the foregoing movement, has lowered the line of action of the spring slightly.

The spring I8, therefore, now tends to collapse the toggle links I and [6. In addition, the contact arm 9 now being against the stop I I to hold the pivot pin I60; against movement, the link extension Ifib converts the pressure of spring I8 to a torque tending to rotate the link It clockwise about the pin Ifia. Thus, if the actuating button 20 is released from the position shown at Fig. 3, the compression spring l8 will break the toggle and move the actuating rod 20 upwardly to its open position by rotating the link It clockwise about the pivot pin [6a. In so rotating, the link Iii draws the link I5 to the right, and by this action rotates the carrier I3 clockwise about its pivot pin I4 to reset the mechanism. If the bimetal I 9 has cooled before resetting movement of the carrier I3, the slidable latch Ita permits resetting movement.

Referring now more particularly to the bimetallic latching detent l9, we have shown at Fig. 4. a perspective view of this detent mounted upon an offset metal base member 25 fixed in the casing I.

The bimetallic member 19 comprises abifurcated bimetallic actuating arm 26 includinggtwo spaced apart coplanar actuating fingers 26a and 26b and mounted at its bight upon the supporting member 25, as by welding. The free ends of the actuating fingers 26a and 2612 are connectcd together by a detent tip 2'! of insulating material, the tip 21 being engaged in operation by the latch member I3a, as shown at Fig. 2. The actuating fingers 26a and 26b are each laterally and reversely bent at their ends to form a pair of bimetallic protective arms 28a and 282). While, these protective arms may be separate pieces fixed to the actuating fingers, they are preferably formed, as shown, as integral reversely directed extensions of the actuating fingers 28a and 26b, and are turned over laterally so that they lie in planes perpendicular to the plane of the actuating arm and in parallel spaced relation with each other. The protective bimetallic arms 28a and 28?: are arranged to be deformed toward the engagement with each other when heated. The movable ends of the protective arms 28a and 281) are provided with contact tips 29a and 291) respectively, which are sufficiently spaced apart so that they do not come into engagement with each other, except upon the occurrence of predetermined excessive overload currents. i

To connect the bimetallic device I9 in series circuit relation between the circuit breaker terminals ii and I2, the contact carrying ends of the protective arms 28a, and 281) are provided with flexible electric conductors or pigtails 30a and 36b respectively, between which the actuating fingers Ma and 26b and the protective arms 28a and 2833 are connected in series circuit relation. As, shown at Fig. 1, the pigtail 39a is connected to the movable contact arm 9, while the pigtail 3819 (not shown) is connected to the terminal member I2. The normal current path through the device I9 is thus from the pigtail 30a, through the arm 28a, the finger a, the finger 2th, the arm 2% to the pigtail 3th, or the reverse.

The bimetallic member of Fig. 4 is shown in plan and elevational view in its no load condition at Figs. 5 and 6, the detent tip 27 and the mounting base 25 being omitted.

Referring now again to Figs. 1, 2 and 3, it will be observed that the bimetallic member Iii is so mounted in the casing I that, when heated, the actuating arm, consisting of the fingers 25a and 26b and the detent tip 27, moves downwardly as viewed in the drawing, to release the carrier member I3. For normal overloads of the order of several times up to ten or twenty times normal current, deformation of the protective arm 28a and 28b is insufficient to bring the contact 29a and 2 db into engagement.

It will now be evident that, upon occurrence of a predetermined excessive overload current traversing the protective bimetallic arms 28a and 28b and the actuating fingers 23a and 23b in series circuit relation, the protective arms are sufiiciently deflected toward each other so that the contacts 28a and 29b come into engagement, thus providing a short circuit path between the pigtails 39a and 3th and shunting the entire-bimetallic member I9 out of the circuit. The device I9 is shown in this condition at Figs. '7 and 8. It will of course be evident that, in operation, the actuating fingers 26a and 2% are sufiiciently deformed to release the latched carrier member i3 before the protectivearmscome into engagement. In practice it has been found that the carrier member I3 is released and the protective arms engaged before the short circuit current through the circuit breaker contacts '6 and l attains its maximum value. In this way, the bimetallic member is protected against the carrying of excessive short circuit currents.

The self-protecting bimetal overload device, described above, is described and claimed in a copending application Serial No. 334,581 filed February 2, 1953, by Eric A. Ericson, and assigned to the same assignee as the instant application. I

It will now be evident to those skilled in the art that we have provided a simplified and improved mechanism, wherein the single operating spring I 8 selectably retains the toggle linkage either extended or collapsed when the carrier member I3 is latched in its normal operating position. The same spring moves the toggle linkage longitudinally to trip the breaker upon release of the carrier member, collapses the toggle linkage after tripping by reason of the controlled movement of the knee pivot of the toggle, and by reason of the extended end of the toggle link to which the spring is connected, exerts upon this link a torque through which the carrier member is automatically returned to its reset position. Finally, the same spring serves to bias the actuating button to a stopped position wherein the casing is sealed when the breaker is closed.

While we have described by way of illustration only a preferred embodiment of our invention, many modifications will occur to those skilled in the art, and we therefore wish to have it understood that we intend in the appended claims to cover all such modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. In a manually operable current responsively tripped electric circuit breaker having a pair of relatively movable cooperating switch contacts, a movable switch member connected to control said contacts, a pair of toggle links having adjacent ends connected together at a knee pivot, latch means for releasably retaining the remote end of one said link at a normally fixed point, means connecting said switch member for actuation to the other said toggle ling, a spring engaging the remote end of said other link to bias said links lengthwise of their extended position toward said normally fixed point, manually operable means for moving said knee pivot across the line of action of said spring means to extend and collapse said toggle links, said contacts being closed when said toggle links are extended and said spring means retaining said toggle links in either extended or collapsed position, and means operable upon release of said latch means with said toggle links extended for moving said knee pivot acros the line of action of said spring.

2. In a manually operable current responsively tripped electric circuit breaker having a pair of relatively movable cooperating switch contacts, a movable switch member connected to control said contacts, a movable carrier member spaced from said switch member, means responsive to current traversing said contacts for normally restraining movement of said carrier member and releasing said carrier in response to a predetermined excessive current, a pair of toggle links connected between said carrier member and said switch member and having a knee pivot, a spring engaging the switch member end of said links to bias theends of'said links together, manually operable means tomove said knee pivot overcenter' with respect to the line of action of said spring to extend and collapse said toggle links, said links when extended moving said switch member to close said contacts and said spring retaining said links either extended or collapsed, said carrier when released permitting lengthwise movement of the extended links thereby to open said contacts, and means for controlling the movement of said knee pivot upon release to move said knee pivot across the line or action of said spring.

3. In a manually operable current responsively tripped electric circuit breaker having a pair of relatively movable cooperating switch contacts, a movable switch member connected to control said contacts, a. movable carrier member spaced from said switch member, means responsive to current traversing said contacts for normally restraining movement of said carrier member and releasing said carrier member in response to a predetermined excessive current, a. pair of toggle links connected between said carrier member and said switch member and having a knee pivot, a spring engaging the switch member end of said links to bias the ends of said links together, manually operable means to move said knee pivot overcenter with respect to the line of action of said spring to extend and collapse said toggle links, stop means limiting movement of said knee pivot in one direction to maintain said links extended, said links when extended moving said switch member to close said contacts and said spring retaining said links either extended or collapsed, said carrier member when released permitting lengthwise movement of the extended links thereby to open said contacts, and means including said spring for applying to the engaged toggle link after release of said carrier a torque in a direction to collapse said links and reset said carrier.

4. In a manually operable current responsively tripped electric circuit breaker having a pair of relatively movable cooperating switch contacts, a movable switch member connected to control said contacts, a movable carrier member spaced from said switch member, means responsive to current traversing said contacts for normally restraining movement of said carrier member and releasing said carrier member in response to a predetermined excessive current, a pair of toggle links connected between said carrier member and said switch member and having a knee pivot, one said toggle link being pivotally connected to said switch member at an intermediate portion of the link and having an extending end portion beyond the pivotal connection, a spring engaging said overhanging end portion to bias the ends of said links together, manually operable means 10! moving said knee pivot over center with respect to the line of action of said spring to extend and collapse said toggle links, said links when extended moving said switch member to close said contacts and said spring retaining said links either extended or collapsed, said carrier member when released permitting lengthwise movement of the extended links thereby to open said contacts, stop means engaging said switch member to limit releasing movement of said links, and means for controlling movement of said one link upon release so that said spring applies to said one link a torque rotating said one link about its pivotal connection with said switch member thereby to reset said carrier member.

5. In a manually operable current responsively trip'ped electric circuit breaker having a pair of relatively movable cooperating switch contacts, a

movable switch member connected to control said contacts, a movable carrier member spaced from said switch member, means responsive to current traversing said contacts for normally restraining movement of said carrier member and releasing said carrier member in response to a predetermined excessive current, a pair of toggle links connected between said carrier member and said switch member and having a" knee pivot, a spring engaging the end of said links opposite said carrier member to bias the ends of said links together, manually operable means to move said knee pivot overcenter with respect to the line of action of said spring to extend and collapse said toggle links, stop means limiting overcenter movement of said knee pivot in one direction to maintain said links extended, said links when extended moving said switch member to close said contacts and said spring retaining said links either extended or collapsed, said carrier member when released permitting lengthwise movement of the extended links thereby to open said contacts, fixed stop means limiting circuit opening movement of said switch member, and means including said spring for rotating the link connected to said switch member about said switch member when said stop is engaged to reset said carrier member.

6. In a manually operable current responsively tripped electric circuit breaker having a pair of relatively movable cooperating switch contacts, a movable switch member pivotally mounted to control said contacts, a movable carrier member spaced from said switch member, means responsive to current traversing said contacts for normally restraining movement of said carrier member and releasing said carrier member in response to a predetermined excessive current, a pair of toggle links connected between said. carrier member and said switch member and having a knee pivot, one said link being pivotally connected to said switch member at a, point intermediate its ends and having an overhanging end portion, a spring engaging said overhanging end portion to bias the ends of said links together, manually operable means to move said knee pivot overcenter with respect to the line of action of said spring to extend and collapse said toggle links, stop means limiting movement of said knee pivot in one direction to retain said links extended, said links when extended moving said switch member to close said contacts and said spring retaining said links either extended or collapsed, said carrier when released permitting lengthwise movement of the extended links thereby to open said contacts, means operable upon release of said carrier to control movement of said knee pivot so that said overhanging end portion of said one link shifts the line of action of said spring across said knee pivot, and stop means limiting circuit opening movement of said switch member, said spring rotating said one link about said switch member upon engagement of said stop means thereby to reset said carrier member.

'7. In a manually operable current responsively tripped electric circuit breaker having a pair of relatively movable cooperating switch contacts, a movable switch member pivotally mounted to control said contacts, a movable carrier member pivotally mounted in spaced relation with said switch member, means responsive to current traversing said contacts for normally restraining movement of said carrier member and releasing said carrier member in response to a predetermined excessive current, a pair of toggle links connected between said carrier member and said switch member and having a knee pivot, one said link being pivotally. connected at an intermediate point to said switch member and having an overhanging end portion, a spring engaging said overhanging end portion to bias the ends of said links together, manually operable means swingably connected to said knee pivot and operable to move said pivot overcenter with respect to the line of action of said spring to extend and collapse said toggle links, stop means limiting movement of said knee pivot overcenter in one direction to maintain said links extended, said links when extended moving said switch member to close said contacts and said spring retaining said links either extended or collapsed, said carrier when released permitting lengthwise movement of the extended links thereby to open said contacts, said knee pivot swinging about said manually operable means in releasing movement thereby to move said knee pivot across the line of action of said spring. and stop means engaging said switch member to limit said releasing movement, said spring acting upon said overhanging end of said one link upon stopping engagement oi said switch member to rotate said one link about said switch member and reset said carrier member.

8. In a manually operable current responsively tripped electric circuit breaker having a pair of relatively movable cooperating switch contacts, a movable switch member pivotally mounted to control'said contacts, stop means for limiting contact opening movement of said switch member, a pair of toggle links having their adjacent ends connected together at a knee pivot, latch means for releasably retaining the remote end of one said toggle link in a normal fixed position, a pivot pin connecting said switch member for actuation to an intermediate point of the other said toggle link, a spring engaging the remote end of said other link to bias said pivot pin toward said normally fixed position and said switch member against said stop means, manually operable means for moving said knee pivot across the line of action of said spring to extend and collapse said toggle links, said contacts being closed when said links are extended and said spring retaining said toggle links either extended or collapsed by overcenter action, and means operable upon release of said latch means with said toggle links extended for controlling the movement of said knee pivot to reverse the spring bias on said toggle links and collapse said toggle, the spring engaging end of said other toggle link beyond said pivot pin acting upon reversal of said bias to rotate said other link about said pivot pin thereby to collapse said toggle and reset said latch means.

9. In a manually operable current responsively tripped electric circuit breaker having a pair of relatively movable cooperating switch contacts, a movable switch member pivotally mounted to control said contacts, stop means for limiting contact opening movement of said switch member, a pair of toggle links having their adjacent ends connected together at a knee pivot, latch means for releasably retaining the remote end of one said toggle link in a normal fixed position, a pivot pin connecting said switch member for actuation to an intermediate point of the other said toggle link, a spring engaging the remote end of said other link to bias said links along their lengths when extended toward said normally fixed position and to bias said switch member against said stop means, manually operable means movable transversely of the lifie of action of said spring and connected by a swingable link to said knee pivot for moving said knee pivot across the line of action of said spring to extend and collapse said toggle links, second stop means limiting over center movement oi said knee pivot in one direction to retain said links extended and said contacts closed, and means responsive to the current traversing said contacts for releasing said latch means, said latch means when released permitting lengthwise movement oi said toggle links when extended thereby to open said contacts, said swingable link moving said knee pivot across the line of action of said spring to collapse said toggle and said spring rotating said other link about said pivot pin to reset said latch means.

10. In a manually operable current responsively tripped electric circuit'breaker' having a pair of relatively movable cooperating switch contacts, a pair of fixed pivots disposed in parallel spaced relation, a switch member mounted upon one said pivot to control said contacts, a fixed stop limiting contact opening movement of said switch member a carrier member mounted on the other said pivot, a first toggle link pivotally connected at one 'end to said carrier member at a point, spaced from said other pivot, a second toggle link having one end connected to the other end of said first to gle link by a knee piv'ot, pivotal means connecting said switch member to an intermediate point of said sec,- ond toggle link, a spring having one end fixed and engaging the other end of said second toggle link to bias the ends of said toggle links toward each other, means normally restraining movement of said carrier member and responmeans movable transversely of the direction of extension of said toggle links, a swin gable link 12 connec n a d kn e pivot to said inanuallr he able means, and second fixed stop means limiting movement of said manually operable means in one direction.

11. In an electric circuit breaker, an enclosing casing having an aperture therein, an actuating mechanism mounted in said casing and including a pair of toggle links having a knee pivot, spring means biasing said links to collapsed position, a manual actuating rod connected to said knee pivot and extending through said aperture, and a cap on said rod positioned to engage said casing upon depression of said rod thereby to limit overcenter movement of said toggle links in one direction and simultaneously to seal said aperture.

12. In an electric circuit breaker, an enclosing casing having an aperture therein, a pair of cooperating switch contacts in said casing an overcenter actuating mechanism in said casing connected to control said contacts, spring means for biasing said mechanism to oppositely overset positions, a reciprocable member extending through said aperture and connected to reverse the position of said mechanism, and stop means mounted on said reciprocable member and engageable with said casing to limit overcenter movement of said actuating mechanism in one direction. and simultaneously to seal said aperture.

RAYMOND N. ROWE.

ERIC A. ERICSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,999,410v Graves Apr. 30, 1935, 2,091,941 Frank Aug. 3-1, 1937 2,148,880 Sattler Feb. 28, 1939; 

